A type of single-use filtering capsule is known today comprising a filtering sachet in paper contained in a closed protective casing perforable at the opposed bases, after the capsule is positioned in the infusion apparatus, for the entry of water and the delivery of the infusion.
This filtering capsule must ensure the protection of the aromatic essence contained in the sachet to prevent both its oxidization in the air and its contamination by external agents.
A high filtering efficiency is demanded of this filtering capsule, a simple and inexpensive structure, and sufficient compactness to be able to be used also in automatic coffee machines.
One of the principal disadvantages of this filtering capsule is due to the fact of having to be subject to well-defined shapes and dimensions in order to preserve the integrity of the filtering sachet during the perforation of the base of the casing from which the infusion is delivered.
In particular it is necessary for the filtering capsule, when positioned in the infusing apparatus for use, to present a closed chamber between the sachet and the base through which the delivery of the infusion occurs, in such a way that the perforator of the infusion apparatus can penetrate this chamber to create the delivery path of the infusion without damaging the sachet.
It is evident that this type of filtering capsule must have, as mentioned above, a minimal bulk not below a certain safety threshold for protecting the filtering sachet, which however, can complicate the use of the filtering capsule in certain types of compact automatic coffee machines.